The present disclosure relates generally to the field of drilling welts and more particularly to steerable drilling tools.
In deviated and horizontal drilling applications it is advantageous to use rotary steerable systems to prevent pipe sticking in the deviated and horizontal sections. It is advantageous to have the drill string rotating to prevent differential sticking and to reduce friction with the borehole wall. The rotary steerable system may have a housing that is substantially non-rotating. The present disclosure describes a downhole adjustable bent housing for rotary steerable drilling.
Directional drilling involves varying or controlling the direction of a wellbore as it is being drilled. Usually the goal of directional drilling is to reach or maintain a position within a target subterranean destination or formation with the drilling string. For instance, the drilling direction may be controlled to direct the wellbore towards a desired target destination, to control the wellbore horizontally to maintain it within a desired payzone or to correct for unwanted or undesired deviations from a desired or predetermined path.
Thus, directional drilling may be defined as deflection of a wellbore along a predetermined or desired path in order to reach or intersect with, or to maintain a position within, a specific subterranean formation or target. The predetermined path typically includes a depth where initial deflection occurs and a schedule of desired deviation angles and directions over the remainder of the wellbore. Thus, deflection is a change in the direction of the wellbore from the current wellbore path.
It is often necessary to adjust the direction of the wellbore frequently while directional drilling, either to accommodate a planned change in direction or to compensate for unintended or unwanted deflection of the wellbore. Unwanted deflection may result from a variety of factors, including the characteristics of the formation being drilled, the makeup of the bottomhole drilling assembly and the manner in which the wellbore is being drilled.
Deflection is measured as an amount of deviation of the wellbore from the current wellbore path and is expressed as a deviation angle or hole angle. Commonly, the initial wellbore path is in a vertical direction. Thus, initial deflection often signifies a point at which the wellbore has deflected off vertical. As a result, deviation is commonly expressed as an angle in degrees from the vertical.
While the disclosed embodiments are susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description herein are not intended to limit the disclosed subject matter to the particular form(s) disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the present disclosure as defined by the appended claims.